Methods:

Flow cytometric enumeration was performed on 20 samples with CLL-like B cells and 10 control specimens using single platform (SP) and two DP tubes A: kappa, lambda, CD5, CD10, CD19, CD38, CD45, CD20 and B: FMC-7, CD23, CD19, CD5, with and without racking to remove doublets. In addition, reproducibility studies were performed.

Results:

Three specimens showed discordant CLL-like B-cell counts relative to the threshold of 5 × 109/L. Bland–Altman analysis demonstrated a systematic bias with DP Tube B > A (5.9%) and SP > DP Tube A (9.5%). The doublet percent varied between specimens, but did not account for the bias between DP tubes. Variation was also seen in enumeration of other cell types, suggesting multiple potential sources of inconsistency.